Precision Combat Arms - This shows some of the things that you can do with your King Arms P90; Echo 1 M4 magazine adapter with H&K style suppressor covering a 420mm 6.01mm
SCG P90 to M4 magazine adapter
SOLD p90 m4 mag adapter | HopUp Airsoft
HI-CAP MAGAZINE ADAPTER 1500 SHOTS FOR P90 SERIES
Cyma M4 magazine adapter for P90 AEG 1,500 BBs - BK - Tactical24 e-Store